1. Field of the Invention
The present invention relates to automotive lubrication oil filters.
It is well known that proper lubrication of automotive engines is perhaps the most critical routine step which can protect the engine from wear and greatly extend the useful life of the engine. Lubricating oil, besides performing its lubricating and cooling functions in the engine, serves to remove acids and other impurities as well as wear residues. They are conventionally removed by filtering elements through which the lubricating oil is continuously circulated and by replacing the lubricating oil with new oil at frequent intervals during the utilization of the engine.
Experience has shown that the filtering elements do not always effectively remove fine metallic particles from the oil medium and that dilution of acids by the volume of the lubricating oil is insufficient to prevent noticeable corrosion of the metal in the engine which accelerates wear. In addition, the fine metallic particles accelerate the clogging of the filtering elements by agglomerating thereon and if they are dislodged from the paper filter element in agglomerated form, they tend to cause more engine damage than if they are uniformly disbursed throughout the volume of oil.
Various attempts have been made to incorporate magnetized particles in the filtering element or to place sheets of magnetized metal within the filter elements. Such approaches complicate the manufacture of the filtering elements and add greatly to the expense of replacing the filter element.
Other attempts have been made to incorporate magnetic means within the oil filter system by utilizing annular blocks at the base of the filter which have limited surface areas for contact with the circulating oil.
2. Prior Art
A vehicle oil filter is disclosed in U.S. Pat. No. 2,890,257 Paton wherein a circular block with a central aperture is provided in the lower portion of the filter casing. The block is formed of a composite of magnetic material and a mass of magnesium metal as an insert. The object is to both collect the ferrous metallic particles and to attempt to neutralize the action of sulfuric acid in the oil. The location at the base of the filter element is such that the oil briefly contacts the inserts, but the limited surface area and restricted position makes the device less than satisfactorily effective in performing its functions.
U.S. Pat. No. 3,279,607 Michaelson shows an oil filter cartridge wherein bars of magnetized material and bars of magnesium are placed in the folds of a corrugated filtering element in an attempt to remove metallic particles and neutralize sulfuric acid as in the Paton reference. The incorporation of the bars or plates within the folds of the filter element limits their effectiveness, particularly if they are not inserted in all of the folds. To do so however, would obviously greatly increase the cost and complexity of the manufacturing of the filter elements which are generally of a disposable nature and of nominal cost.
A magnetized helical coil to remove metallic particles from the oil is located externally of the filtering elements in U.S. Pat. No. 3,727,761 Aspinwall et al. in a complicated hydraulic filter structure.
Also of interest in U.S. Pat. No. 2,893,561 Duzich which discloses various sheet paper or batts of fibrous filter elements in which magnetized particles are diffusely located in order to attract metallic particles from the oil being filtered.
In U.S. Pat. No. 4,218,320 Liaw, an oil filter is disclosed in which an attached accessory wrap of either an electro-magnet or permanent magnet is wound around the main body of the filter in order to attract fine iron particles to it to prevent them from penetrating the rolled filter element. This device serves to lengthen the duration of the usefulness of the filter paper. It is wound externally of the outer side of the filter can body and does not come in contact with the lubricating oil.
U.S. Pat. No. 3,342,339 Riolo discloses a conventional casing structure with permanent magnets fixedly incorporated into the filter structure.
U.S. Pat. No. 2,795,333 Kennedy relates to a fuel filter and discloses a spring used to retain a treating element.